Refrigerator and/or freezer

ABSTRACT

The present invention relates to a refrigerator and/or freezer with a heat transfer circuit, which comprises a magnetic cooler, a pump for delivering the heat transfer medium, a cold heat exchanger for cooling the refrigerating and/or freezing space of the appliance, and a warm heat exchanger for cooling the heat transfer medium, wherein the warm heat exchanger has a cross-sectional area between 14 mm 2  and 54 mm 2 .

BACKGROUND OF THE INVENTION

The present invention relates to a refrigerator and/or freezer with aheat transfer circuit, which comprises a magnetic cooler, a pump fordelivering the heat transfer medium, a cold heat exchanger for coolingthe refrigerating and/or freezing space of the appliance and a warm heatexchanger for cooling the heat transfer medium.

In the case of magnetic cooling, a heat transfer medium flowing througha heat transfer circuit is heated and cooled by utilizing the so-calledmagnetocaloric effect. The process steps performed usually include themagnetization, the extraction of heat, the demagnetization and the colduse, which steps are repeated continuously.

For performing these process steps, different methods are known. It isconceivable, for instance, to use a stationarily arranged magnetocaloricmaterial and one or more rotating magnets, which periodically magnetizeand demagnetize the magnetocaloric material, wherein the same undergoesheating and cooling. Heating and cooling of the magnetocaloric materialare utilized for heating or cooling the heat transfer medium flowingthrough the magnetic cooler. It is also conceivable to stationarilyarrange the magnet or magnets and movably arrange the magnetocaloricmaterial or to provide the magnetocaloric material in the heat transfermedium

A conceivable heat transfer circuit comprises a so-called cold heatexchanger, said magnetic cooler, a warm heat exchanger and a pump fordelivering the heat transfer medium through the heat transfer circuit.During the magnetization of the magnetocaloric material, the sameundergoes heating. The heat is transferred to the heat transfer medium.By means of the pump, the heat transfer medium then is delivered intothe warm heat exchanger, in which it is cooled. Subsequently, thefurther cooling of the heat transfer medium is effected in thedemagnetized and therefore cooled region of the magnetic cooler. Theheat transfer medium cooled in this way then traverses the cold heatexchanger, which serves for cooling the goods to be refrigerated and/orfrozen. The heat transfer medium is heated thereby and then is againheated further in the magnetized region of the magnetic cooler. Finally,it again reaches said warm heat exchanger via the pump.

SUMMARY OF THE INVENTION

It is the object underlying the present invention to develop arefrigerator and/or freezer as mentioned above such that its energyconsumption is reduced as compared to known appliances.

This object is solved by a refrigerator and/or freezer with the featuresherein.

Accordingly, it is provided that the warm heat exchanger has across-section between 14 mm² and 54 mm². For instance, it can beprovided that the warm heat exchanger has a cross-section between 24 mm²and 44 mm², preferably between 30 mm² and 38 mm², and particularlypreferably between 32 mm² and 36 mm². A particularly preferred value isabout 34 mm².

This invention furthermore relates to a refrigerator and/or freezer withthe features of claim 3. Accordingly, it is provided that the cold heatexchanger has a cross-section between 30 mm² and 70 mm². For instance,it can be provided that the cold heat exchanger has a cross-sectionbetween 40 mm² and 60 mm², preferably between 46 mm² and 54 mm², andparticularly preferably between 48 mm² and 52 mm². A particularlysuitable value for the cross-sectional area of the cold heat exchangeris about 50 mm².

In accordance with the present invention, the term “cross-section” isunderstood to be the internal cross-section, i.e. the flow cross-sectionof the heat exchanger(s) available for the heat transfer medium. Theindicated values can be absolute values or also mean values.

In principle, the advantage of a great cross-section consists in thecomparatively low pressure loss and a resulting low energy consumptionof the pump delivering the heat transfer medium. The advantages of asmall cross-section consist in the comparatively small filling volume,which leads to a short defrosting phase and involves an improvedrefrigerating capacity. By means of the present invention, an optimumcompromise is achieved between the refrigerating capacity on the onehand and the energy consumption of the pump on the other hand. Ingeneral, a low energy consumption of the magnetic cooler is achieved bythe present invention in a refrigerator and/or freezer.

Particularly advantageously, both the cold heat exchanger and the warmheat exchanger have the above-mentioned preferred cross-sectionalvalues. Accordingly, a preferred aspect of the invention consists inthat the refrigerator is configured in accordance with the descriptionherein.

The cross-sectional area of the warm and/or cold heat exchanger can beconstant, i.e. hardly change along the flow path or not at all.

However, it is also conceivable that the cross-sectional area of thewarm and/or of the cold heat exchanger is variable, i.e. changes alongthe flow path of the heat transfer medium through the heat exchanger(s),and that the cross-sectional values are mean values.

In a further aspect of the invention it is provided that the warm heatexchanger and/or the cold heat exchanger is made of one tube or of twoor more than two tubes, which can extend in parallel. Thus, it isconceivable to distribute the heat transfer medium to several tubes.

If the warm heat exchanger and/or the cold heat exchanger is made of twoor more than two tubes, the cross-sectional values can be the entirecross-sectional area of the two or more than two tubes, i.e. the sum ofthe cross-sections of the individual tubes. In this case, a plurality oftubes with a smaller cross-sectional area thus could be provided insteadof one tube.

The tubes can be round in cross-section or also have any othercross-sectional shape.

The present invention furthermore relates to a refrigerator and/orfreezer with the following features. Accordingly, it is provided thatthe cross-sectional area of the cold heat exchanger is greater than thecross-sectional area of the warm heat exchanger. If these arecross-sectional areas which vary along the flow path, it can providedthat the mean value of the cross-sectional area of the cold heatexchanger is greater than the mean value of the cross-sectional area ofthe warm heat exchanger. However, the invention of course also covers anembodiment with constant or substantially constant cross-sectionalareas, i.e. cross-sectional areas which do not or not substantially varyalong the flow path. It is conceivable, for instance, that thecross-sectional area of the cold heat exchanger exceeds that of the warmheat exchanger by values in the range from >0 to 25 mm².

In principle, however, the invention also covers the case that thecross-sectional areas of both heat exchangers are identical.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages of the invention will be shown withreference to an embodiment illustrated in the drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference numeral 10 designates the magnetic cooler, which comprises twoheat exchanger units 12, 14, which can be configured as a constructionalunit or also separate from each other.

The heat exchanger untis 12, 14 are made of a magnetocaloric material orinclude such material.

They are cyclically magnetized and demagnetized, for which purpose anon-illustrated magnet is provided, which rotates about the heatexchanger units 12, 14. Depending on the position of the magnet, theheat exchanger units 12, 14 are magnetized or demagnetized, whichresults in the heating or cooling thereof and also in the heating orcooling of the heat transfer medium which flows through the heatexchanger units 12, 14.

The heat transfer circuit of the refrigerator and/or freezer furthermoreincludes a cold heat exchanger 20, which is arranged in therefrigerating and/or freezing space or in the vicinity of therefrigerating and/or freezing space of the appliance and provides forcooling the same. A warm, preferably air-cooled heat exchanger 50 isarranged on the outside of the appliance and serves to dissipate heatfrom the heat transfer medium to the surroundings.

The pump 100 provides for the flow of the heat transfer medium throughthe illustrated heat transfer circuit.

Downstream of the cold heat exchanger 20 a valve 40 is arranged, anddownstream of the warm heat exchanger 50 a further valve 30 is arranged.The valves are for instance bistable or monostable valves. In coolingoperation, the valves 30, 40 are actuated such that the heat transfermedium from the warm heat exchanger 50 always gets into that heatexchanger unit 12, 14 which is just cooled or demagnetized, and fromthere into the cold heat exchanger 20. The valve 40 is actuated suchthat the heat transfer medium which has traversed the cold heatexchanger 20 is supplied to that heat exchanger unit 12, 14 which is inthe magnetized condition and therefore heated.

In the embodiment illustrated here it is provided that the mean flowcross-section of the cold heat exchanger 20 is about 50 mm² and that themean flow cross-section of the warm heat exchanger 50 is about 34 mm².

In this way, it is ensured that the energy consumption of the pump iscomparatively low and the refrigerating capacity of the heat exchangercomparatively high. The present invention represents an optimumcompromise between these parameters and thus allows to provide arefrigerator and/or freezer with magnetic cooling, which has a lowenergy consumption.

The cold heat exchanger and/or the warm heat exchanger can be made ofone single tube or of two or also more than two tubes which aretraversed by the heat transfer medium. The two or more than two tubescan be installed in parallel. However, this is not absolutely necessary.

1. A refrigerator and/or freezer with a heat transfer circuit, whichcomprises a magnetic cooler, a pump for delivering the heat transfermedium, a cold heat exchanger for cooling the refrigerating and/orfreezing space of the appliance and a warm heat exchanger for coolingthe heat transfer medium, wherein the warm heat exchanger has across-sectional area between 14 mm² and 54 mm².
 2. The refrigeratorand/or freezer according to claim 1, wherein the warm heat exchanger hasa cross-sectional area between 24 mm² and 44 mm², preferably between 30mm² and 38 mm², and particularly preferably between 32 mm² and 36 mm².3. A refrigerator and/or freezer with a heat transfer circuit, whichcomprises a magnetic cooler, a pump for delivering the heat transfermedium, a cold heat exchanger for cooling the refrigerating and/orfreezing space of the appliance and a warm heat exchanger for coolingthe heat transfer medium, wherein the cold heat exchanger has across-sectional area between 30 mm² and 70 mm².
 4. The refrigeratorand/or freezer according to claim 3, wherein the cold heat exchanger hasa cross-sectional area between 40 mm² and 60 mm², preferably between 46mm² and 54 mm², and particularly preferably between 48 mm² and 52 mm².5. The refrigerator and/or freezer according to claim 3, wherein theappliance is configured in accordance with the warm heat exchangerhaving a cross-sectional area between 14 mm² and 54 mm².
 6. Therefrigerator and/or freezer according to claim 1, wherein thecross-sectional area of the warm and/or of the cold heat exchanger isconstant.
 7. The refrigerator and/or freezer according to claim 1,wherein the cross-sectional area of the warm and/or of the cold heatexchanger is variable and a mean value values.
 8. The refrigeratorand/or freezer according to claim 1, wherein the warm heat exchangerand/or the cold heat exchanger is made of one tube or of two or morethan two tubes which preferably extend in parallel.
 9. The refrigeratorand/or freezer according to claim 8, wherein the warm heat exchangerand/or the cold heat exchanger is made of two or more than two tubesextending in parallel and the cross-sectional value is the totalcross-sectional area of the two or more than two tubes.
 10. Arefrigerator and/or freezer with a heat transfer circuit, whichcomprises a magnetic cooler, a pump for delivering the heat transfermedium, a cold heat exchanger for cooling the refrigerating and/orfreezing space of the appliance and a warm heat exchanger for coolingthe heat transfer medium, wherein the cross-sectional area of the warmheat exchanger is smaller than the cross-sectional area of the cold heatexchanger.
 11. The refrigerator and/or freezer according to claim 10,wherein the appliance is configured in accordance with the warm heatexchanger having a cross-sectional area between 14 mm² and 54 mm². 12.The refrigerator and/or freezer according to claim 4, wherein theappliance is configured in accordance with the warm heat exchangerhaving a cross-sectional area between 14 mm² and 54 mm².
 13. Therefrigerator and/or freezer according to claim 12, wherein thecross-sectional area of the warm and/or of the cold heat exchanger isconstant.
 14. The refrigerator and/or freezer according to claim 2,wherein the cross-sectional area of the warm and/or of the cold heatexchanger is constant.
 15. The refrigerator and/or freezer according toclaim 3, wherein the cross-sectional area of the warm and/or of the coldheat exchanger is constant.
 16. The refrigerator and/or freezeraccording to claim 4, wherein the cross-sectional area of the warmand/or of the cold heat exchanger is constant.
 17. The refrigeratorand/or freezer according to claim 5, wherein the cross-sectional area ofthe warm and/or of the cold heat exchanger is constant.
 18. Therefrigerator and/or freezer according to claim 17, wherein thecross-sectional area of the warm and/or of the cold heat exchanger isvariable and a mean value.
 19. The refrigerator and/or freezer accordingto claim 16, wherein the cross-sectional area of the warm and/or of thecold heat exchanger is variable and a mean value.
 20. The refrigeratorand/or freezer according to claim 15, wherein the cross-sectional areaof the warm and/or of the cold heat exchanger is variable and a meanvalue.